CORROSION MECHANISMS OF IRON IN CONCENTRATED ACIDIC ZINC-CHLORIDE MEDIA

A mechanism for the anodic dissolution of iron in concentrated zinc ch loride media is proposed as an ECE mechanism. The rate determining ste p is the formation of a Fe-Cl reaction intermediate. This mechanism wa s found to be suitable for interpretation of kinetic electrochemical p arameters obtained in these solutions. Radiotracer studies showed that the iron interface is saturated with cr at low concentrations which i s responsible for the change in the iron dissolution mechanism. The ph enomenon of the region of non-polarizability is interpreted in terms o f the electrochemical desorption of the Cl- ion at high dissolution ra tes. The hydrogen evolution reaction was found to be inhibited due to the underpotential deposition of zinc. The effect of decreasing water activity in solutions of high ionic strength is found to significantly decrease i(o,Fe,) i(o,H+) and i(corr) values.